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Unformatted text preview: 11/16/2008 1 NONTRADITIONAL MACHINING AND THERMAL CUTTING PROCESSES Mechanical Energy Processes Electrochemical Machining Processes Thermal Energy Processes Chemical Machining Application Considerations Nontraditional Processes Defined A group of processes that remove excess material by various techniques involving mechanical, thermal, electrical, or chemical energy (or combinations of these energies) but do not use a sharp cutting tool in the conventional sense Developed since World War II in response to new and unusual machining requirements that could not be satisfied by conventional methods Why Nontraditional Processes are Important Need to machine newly developed metals and non-metals with special properties that make them difficult or impossible to machine by conventional methods Need for unusual and/or complex part geometries that cannot easily be accomplished by conventional machining Need to avoid surface damage that often accompanies conventional machining Classification of Nontraditional Processes by Type of Energy Used Mechanical- erosion of work material by a high velocity stream of abrasives or fluid (or both) is the typical form of mechanical action Electrical- electrochemical energy to remove material (reverse of electroplating) Thermal thermal energy usually applied to small portion of work surface, causing that portion to be removed by fusion and/or vaporization Chemical chemical etchants selectively remove material from portions of workpart, while other portions are protected by a mask Mechanical Energy Processes Ultrasonic machining Water jet cutting Abrasive water jet cutting Abrasive jet machining Ultrasonic Machining (USM) Abrasives contained in a slurry are driven at high velocity against work by a tool vibrating at low amplitude and high frequency Tool oscillation is perpendicular to work surface Tool is fed slowly into work Shape of tool is formed in part 11/16/2008 2 Figure 26.1 - Ultrasonic machining USM Applications Hard, brittle work materials such as ceramics, glass, and carbides Also successful on certain metals, such as stainless steel and titanium Shapes include non-round holes, holes along a curved axis Coining operations - pattern on tool is imparted to a flat work surface Water Jet Cutting (WJC) Uses a fine, high pressure, high velocity stream of water directed at work surface for cutting Figure 26.3 - Water jet cutting WJC Applications Usually automated by CNC or industrial robots to manipulate nozzle along desired trajectory Used to cut narrow slits in flat stock such as plastic, textiles, composites, floor tile, carpet, leather, and cardboard Not suitable for brittle materials (e.g., glass) WJC advantages: no crushing or burning of work surface, minimum material loss, no environmental pollution, and ease of automation Abrasive Water Jet Cutting (AWJC) When WJC is used on metals, abrasive...
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This note was uploaded on 05/05/2011 for the course IE 370 taught by Professor Chunghorng,r during the Spring '08 term at Purdue University-West Lafayette.
- Spring '08